Question

I’m implementing right now some syscalls from unistd.h and fcntl.h (open, read, close, e.t.c)
Some of the require special flags and macros (O_CREAT, O_RDWR)

Is there a way to include only the flags and macros without the function definitions
from unistd.h and fcntl.h?

Thanks

Answer 1

Perhaps the -imacros option to gcc is what you are looking for.

-imacros FILE

 Exactly like `-include`, except that any output produced by
 scanning FILE is thrown away.  Macros it defines remain defined.
 This allows you to acquire all the macros from a header without
 also processing its declarations.